1. Field of the Invention
The field of the invention is data processing, or, more specifically, methods, systems, and products for transparent content addressable data storage and compression for a file system.
2. Description of Related Art
Content addressable storage, sometime called associative storage, is a kind of computer memory storage in which items of data are stored by analysis of their content rather than by fixed memory addresses or locations. Traditional approaches to content addressable storage confront a dilemma: content addressable methods can be efficient in terms of CPU utilization if they use fixed memory block sizes, but using a fixed memory block size is an inefficient use of underlying storage media. Traditional methods of content addressable storage also typically do not provide for data compression, although, in terms of efficient use underlying storage media, it would be beneficial if they did. There is therefore an ongoing need for improvement in the area of content addressable storage.
Transparent file system compression schemes have been implemented in a number of ways in existing systems, including cramfs, ziosfs, and ntfs/vfat. These schemes compress data on a per-block basis, typically using industry standard compression techniques, zip, gzip, and so on, for example, and are limited to using small block sizes due to performance constraints. Because compression algorithms can only be as effective as the amount of entropy in their input, high compression ratios are less likely to be achieved when using smaller amount of input data.